This proposal seeks to define, in situ, then isolate and functionally characterize the immunologic and nonspecific effector responses of lymphocytes present in periodontal lesion cellular infiltrates. The first experimental approach will be to characterize cellular infiltrates of periodontal lesions in situ by morphological, cytochemical, and immunopathological assessments. The second experimental approach will be to recover gingival lymphocytes and other inflammatory cells, from diseased gingiva, then characterize these cells using surface markers. Thirdly, the in vitro effector responses presumed to be correlates of the in vivo disease will be assessed using isolated gingival lymphocytes.